Rapping device



Jan. 1, 1946. J HAMILTON r 2,392,088

RAPPiNG DEVICE Filed July 30, 1943 4 Sheets-Sheet 1 m I08 4 0 i 8/ 1946- J. H. HAMILTON ETAL 2,392,033

RAPPING' DEVICE Filed July 30, 1943 4 Sheets-Sheet 2 lJ [Iii-P m J Jan. 1, 1946. J. H. HAMILTON mm. 2, 9

RAPPING DEVICE Filed July 30, 1943 4 Sheets-Sheet 3 Illlll ml. [m- \-/AIIIIIII $3, L\\\\\\\\\\\\\\\\\\\\| Ix. lW//////////////// A| lV/A Patented Jan. 1, 1946 RAPPING DEVICE James Hugh Hamilton, Burbank, Calif and Harry J. White, Cambridge, Mass; said Hamilton asslgnor to Western Precipitation Corporatlon, Los Angeles, Calif., a corporation of Calliornia, and said White assignor to Research Corporation, New York, N. Y., a corporation of New York Application July 30, 1943, Serial No. 496,808

Claims.

This invention relates to apparatus for rapping the material collecting members of gas cleaning devices and particularly-to apparatus for rapping the electrodes of electrical precipitators.

A principal object of the invention is the provision of an efficient and eflective rapping device.

Another object of the invention is the provision of a simple, fluid-pressure actuated rapper with a minimum of moving parts.

A further object of the invention is the provision of a system for insuring the regular, uniform and automatic rapping of the electrodes of electrical precipitators.

The invention comprises a fluid-pressure actuated rapper including a cylinder, a free piston in the cylinder and means for intermittently supplying a fluid pressure medium, such as com pressed air, to the cylinder to bring about an impact of the piston against a striking surface at one or both ends of the piston.

The invention also comprises means for supplying a fluid pressure medium, such as compressed air, to a plurality of rapping devices in predetermined amounts and at predetermined intervals, typically including a rotary multiple port valve device for controlling the flow of compressed air from a single source to a plurality of rapping devices.

For the purpose of illustration the invention will be further described with reference to the 9.0- companying drawings showing a rapping device and system embodying the principles of the invention applied to an electrical precipitator.

In the drawings:

Fig. 1 is a diagrammatic plan view with parts broken away of the top of an electrical precipitator including the rapping system of the invention;

Fig. 2 is a side elevation of the rapping system of Fig. 1 in partial section along line 2-4 of Fig. 1;

Fig. 3 is atransverse sectional elevation on line 3-3 of Fig. 1;

Fig. 4 is a fragmentary enlarged view of a portion of the high tension electrode frame assembly of the precipitator;

Fig. 5 is a sectional elevation of a rapping device of the invention particularly adapted to the rapping of the collecting electrode assemblies of the precipitator;

Fig. 6 is a sectional elevation of a rapping device of the invention particularly adapted to the rapping of the high tension or precipitating electrode assemblies of the precipitator.

Fig. 7 is a sid elevation in partial section of the rotary control valve of the invention;

Fig. 8 is a transverse section on line 8-8 of Fi '7;

Fig. 9 is a plan view of the control valve;

Fig. 10 is a perspective view of the plug member of the control valve, and

Fig. 111s a modified form of the rappin device of the invention adapted for rapping collecting electrode assemblies. I The electrical precipitator to which the rapping device of the invention is applied for the purposes of the invention comprises, as shown more particularly in Figs. 1 and 3 of the drawings, a shell iii, providing a passage for the horizontal flow of gas therethrough and including a roof Ii, sides I! and-material collecting hoppers l3.

Mounted within the shell iii are a plurality of vertical, longitudinally-extending collecting electrode-assemblies 20 and complementary precipitating electrode assemblies.

The collecting electrode assemblies comprise a plurality of V-shaped elements 2| mounted in suitable supporting framework and carried at their upper ends in channel members 22 which rest loosely at each end on transverse support members attached to shell It, as shown for example in application Serial No. 450,711, filed July 13, 1942, of Harry J. White, now Patent 2,369,877, dated Feb. 20, 1945.

The precipitating electrode assemblies 30 comprise a plurality of wire or rod elements 3| attached to horizontal top members 32 and bottom members 33 .which rest on transverse top members 34 and bottom members 35, respectively, of the high tension electrode frame. This frame is carried by means of lateral vertical supports 40, 4| from transverse bus bars 36 mounted on insulators 31 in insulator housings 38 at each end of the shell.

To provide a resilient support for the high tension electrode assemblies which is structurally firm but will not transmit an undue amount of vibration to the insulator supports, the horizontal frame members 34 are spring mounted on the vertical supporting member 40, 4|, as shown in detail in Fig. 4 of the drawings. Externally threaded sleeve 42 is fastened to the outside of the a frame member 40 '(or 4i) and adjustable sleeve 43 is threaded thereto and held in position by means of lock nut 44. Frame member 34 is supported on the upper end of adjustable sleeve 43 through washer 45, coil spring 46, and washer 41. The hollow tubular member 40 is provided with a horizontal nipple 48 for supplying compressed air to the rapping device as described hereinafter.

In the particular form of precipitator shown 'by way of example in the drawings, the collecting electrode assemblies are arranged in two parallel groups each comprising eight parallel vertical collecting electrode assemblies 22 and the precipitating electrode assemblies are correspondingly grouped into two main assemblies each including seven vertical curtains of high tension electrode members 2| positioned in alternate vertical planes parallel to the collecting electrode assemblies. A collecting electrode rapper I is provided for each of the sixteen collecting electrode assemblies and a precipitating electrode rapper I is provided at each end of each of thetwo main precipitating electrode assemblies. 1

Collecting electrode rapping device 50, as shown in detail in Fig. 5 of the drawings, comprises a cylinder consisting of a cylindrical section: 5| welded to a base plate 52 and closed at its upper end by cap 53 having a central exhaust port 54. Within the cylinder is a free piston 55 having a slight clearance with the cylinder walls and resting in the normal vertical position of the device on anvil 58 carried by base plate 52. Compressed air supply port 51 opens into the cylinder below the piston in its resting position.

The rapping device 50 is bolted to channel member 22 midway of its length bymeans of bolts passing through base plate 52, roof member ll, spacer plate 58, channel member 22, and backing plate 59.

On admission of a slug oi compressed air of short duration into cylinder 5| through port 51 the piston 55 is raised from its seat and caused to strike cap 54 with a force determined by the pressure of the air and the size and clearance of the piston. The compressed air escapes from the cylinder through the clearance between the cylinder and the piston and out through exhaust port 54. Groove 55' in the piston prevents sealing oi! oi the exhaust port at the top position of the piston. The piston then drops back on anvil 56 with a force determined by its weight and clearances.

The high tension electrode rapping device 50, shown in detail in Fig. 6 of the drawings, comprises a cylinder member 8|, welded to a base plate 62 having an exhaust port 52 therein. The cylinder is closed at its lower. end by cap 54 having an inlet port 85. Positioned in the cylinder is a free piston 68, which in the normal position of the device as shown rests on the cap 84. The rapping device is attached to transverse member 24 oi the high tension electrode assembly by means of bolts passing through the base plate 62, spacer plate 61 and member 24.

The mode of operation of the device is similar to that described above for the collecting electrode rapping device 50, the force 01' the impact oi the piston 66 againstthe base plate 62 and cap 54 being determined by the air pressure and the size and clearances of the piston.

The rapper actuating and control system of the invention comprises one or more multiple port rotary valves III preferably driven by an electric motor 90 through reduction gear 9|, as shown in Fig. 1 oi the drawings.

A typical form of the control valve is shown in detail in Figs. 7-10 of the drawings. It comprises a cylinder Ii having an inlet port I2 and a suitable number, in the embodiment shown-fiveor outlet ports ll, 82, 83, 84, 85, spaced lengthwise of the cylinder from the inlet port. The cylinder aaaaoss is lined with bearing liner I3 having apertures corresponding to the inlet and outlet ports of the cylinder and iixed in position by set screws 14.

Mounted for rotation in the cylinder'is rotary plug 15 having an annular channel 18 positioned for continuous communication with the inlet port 12, a longitudinal channel 11, one or more radial channels II connecting annular channel 10 with longitudinal channel 11, and a plurality oi! radial channels I! communicating with longitudinal channel I1 and positioned to communicate with outlet ports 8|, 22, 82, 24 and 85 at successive radial positions oi the rotating plug. It will be seen that if a source of compressed air is connectedto inlet port 12 successive slugs of compressed .air will be delivered intermittently through outlet ports ll, 22, I2, 84 and 25 in regular succession.

In the actuating and control system as shown I in Figs. 1 and 2f 0! the drawings, the slugs of compressed air from outlet ports ll of each of the valves I! are delivered to the high tension electrode rappers I on one side 01' the precipitator through conduits IM, while the slugs of compressed air from outlet ports 82, 22, 84, II are delivered to adjacent pairs of collecting electrode rappers 50 through conduits I02, ill, I24, I05, respectively. The system operates eiiectively with compressed air at a pressure of 80 to 100 pounds per square inch and with a speed of rotation of the distributing valve of 20 to revolutions per minute. Advantageousiy the distributing valve may be controlled by an automatic timing switch (not shown) which actuates the valve, for example, for periods 01. 10 to 15 seconds at intervals of 15 to 20 minutes. The automatic control also advantageously shuts oh the main air valves I08 between cycles of operation.

Conduits 100 are connected to the upper ends of tubular high tension electrode support members III by rubber tubes I00 and nipples 42 or the tubular support members are connected to the inlet ports of rappers I. by rubber tubes I" (Fig. 3). Rubber tubes Hi0 serve to insulate the high tension electrode assemblies from the rapping control system.

It will be seen that the system of the invention provides a regular succession of rapping impacts of predetermined i'orce directly applied at selected portions of the collecting and high tension electrodes of the assemblies.

By means of the construction shown in Fig. 11 oi the drawings, the root member ll of the precipitator chamber may be eliminated from the impact transmission assembly of the collecting electrode rapper as shown in Fig. 5. In this modification the rapper device 0, comprising a cylinder Ill, base plate H2, cap ill, anvil Ill and free piston H5, is positioned in an opening cut in the roof ll of the precipitator and is enclosed by a housing H6 attached to the root II. A flexible conduit H1 passing through housing H6 supplies compressed air to the inlet port 8 of the rapper. The rapper is attached to collecting electrode support member 22 by means of bolts passing through base plate 2, member 22, and backing plate H9, In the form of rapper shown in Fig. 11, the cap H2 contains lateral outlet ports I20 instead 01' the central outlet port shown in Fig. 5. In the rappers shown in the drawings, release of air pressure below the pistons may be eil'ected by means of vents provided in the lower part of the cylinder. When such vents are provided, the clearance between the piston and the cylinder may be reduced.

We claim:

1. In an electricalprecipitator, an electrode assembly rapping device comprising a vertical cylinder rigidly mounted on a member of said electrode assembly, a free piston positioned within said cylinder and having a limited clearance with the walls thereof, means for admitting fluid pressure impulses into said cylinder below said piston in the at rest osition thereof, and an outlet port in the upper end of said cylinder.

2. In an electrical precipitator including collecting electrode and precipitating electrode assemblies, a plurality of vertical cylinders rigidly attached to members of the electrode assemblies, each of said cylinders having a free piston positioned therein, fluid pressure inlet and outlet ports in said cylinder below and above said free piston, respectively, and means for supplying intermittent fluid pressure impulses in succession to the inlet ports of said cylinders.

3. In an electrical precipitator including collecting electrode and precipitating electrode assemblies, a vertical cylinder rigidly attached to an electrode support member, a free piston positioned within said cylinder, fluid pressure inlet and outlet ports in said cylinder below and above said free piston, respectively, and flexible conduit means for supplying intermittent fluid pressure impulses to the inlet port of said cylinder.

4. In an electrical precipitator including collecting electrode and precipitating electrode assemblies, a vertical cylinder rigidly attached to an electrode support member and extending freely through a wall of said precipitator, a free piston positioned within said cylinder, fluid pressure inlet and outlet ports in said cylinder below and above said free piston, respectively, and flexible conduit means for supplying intermittent fluid pressure impulses to the inlet ort of said cylinder.

5. In an electrical precipitator including collecting electrode and precipitating electrode assemblies, a vertical cylinder rigidly attached to an electrode support member and extending freely through a wall of said precipitator, a free piston ositioned within said cylinder, fluid pressure inlet and outlet ports in said cylinder below and above said free piston, respectively, and conduit means for supplying intermittent fluid pressure impulses to the inlet port of said cylinder.

JAMES HUGH HAMILTON. HARRY J. WHITE. 

